I have the Taylor K-2006.

There are two methods to do the FAS/DPD:

10ml sample for 1 drop = .5ppm.
25ml sample for 1 drop = .2ppm

Is it possible to use the 25ml version of the test to ONLY test for CC without doing the FC test first?

My intent would be to test a low level CC while FC is high without using a ton of R-871 solution.

It seems like it would be pretty common to have shock level FC (15+) and want to accurately measure small CC (e.g. while trying to fight algae).

This example would lead to using 75+ drops of R-871 just to get to the CC test.

Nope, there isn't any way to test CC without first testing FC.

The best you could do at saving work/reagent is to not bother counting the drops during the FC test (which doesn't really help anything).

There isn't usually any point in measuring CC by 0.2 unless you have a commercial pool. I am not sure why you would want to do that.

Got it. Thanks Jason!

I really can't think of any reason why one would want to test to the 0.2 ppm level. Most of our work is sufficient to the 0.5 ppm reading.

When it comes to shocking, the most important part is knowing what your FC should be based on your current CYA reading. You dial it up there and hold it until your overnight FC loss test is successful. Usually, a CC reading is the last thing to take into account. For example, if you know that your target FC is 11 ppm, and overnight you lose 3 ppm, then there isn't much reason to test for CC since you are still losing FC without the effects of UV rays. You aren't done yet. Does this make sense?

I would test only with a 10 ml sample. This saves your R-0871 more than anything.